I'm so confused and stuck

So, Lets start off my saying I am currently 16 days late, had some spotting 5 days before my period was due that lasted almost 3 days. When I was 5 days late, I had a Blood test done at an Urgent care that came back negative, But ive been having faint positives since the spotting started. I've had slight episodes of Nausea, But the main thing has been me cramping for the last 2 weeks, No bleeding, And lower back pain. Fatigue and diarrhea have also been real ! Anyways, I also got a super faint positive on that .88 cent pregnancy test from Walmart. I'm not sure what is going on, But I've heard some women just dont metabolize correctly making it hard to detect HCG. I dont know ! The earliest my OBGYN can get me in is next month. I'm hoping this isn't a chemical pregnancy, But I would just like honest reassurance, your own person experience, And opinions. I'm highly confused.